Axial flow rotors for fluid machines



Aug. 13, 1957 D. J. CLARKE AXIAL FLGW RQ'E'ORS FOR FLUID MACHINES FiledSept. 16, 1950 2 Shoots-Sheet 1 nlliiili I'll AHHHH 52 mvszvrox.

Aug. 13, 1957 AXI Filed Sept. 16, 1950 D. J. CLARKE 2,802,619

AL FLOW ROTORS FOR FLUID MACHINES 2 Sheets-Sheet 2 United States PatentAXIAL FLOW ROTORS FOR FLUID MACHINES Daniel J. Clarke, Bay City, Mich,assignor to The Stalker Development Company, Bay City, Mich, acorporation of Nfichigarl Application September 16, 1950, Serial No.185,216

7 Claims. (Cl. 230-134) This invention relates to rotors and stages ofblades for fluid machines such as compressors and turbines and the like.

It has for an object the provision of an assembly or stage of bladeswhich is light in weight and economical to produce.

Other objects will appear from the description, drawings and claims.

The above objects are accomplished by means which are illustrated in theaccompanying drawings in which:

Fig. l is a fragmentary axial view of a rotor;

Fig. 2 is a fragmentary axial section of a rotor according to thisinvention;

Fig. 3 is a fragmentary axial view of a blade plate with the bladeblanks spaced peripherally;

Fig. 4 is a fragmentary axial view of a core plate;

Fig. 5 is a fragmentary view of two rotor blades, one showing a bladeblank only partially wrapped about a blade core;

Fig. 6 is a section of a blade along 66 in Fig. 5;

Fig. 7 is a fragmentary axial section of a rotor with individual bladeblanks; and

Fig. 8 is a perspective view of an individual blade blank after folding.

The invention of this application represents a further development ofthe inventions described in the applications filed by Edward A. Stalker,Serial No. 38,904, new Patent No. 2,649,278, and Serial No. 167,981, nowPatent No. 2,772,851.

This invention provides a bladed rotor which is light in weight andeconomical to produce. For instance it may weigh only about 40% of solidblade rotors and can be produced at about 25% of the cost.

The saving in weight in the blades by making them hollow whilesignificant is not the major efiect. However by saving weight in theblades the structure supporting the blades may be made light since theprincipal load coming on this hub structure is due to centrifugal force.

The very great saving in weight is achieved by making the blades of thinwalls. directly to the hub structure without the intervening agency of ablade hub which would add weight and require a heavy rotor hubstructure. In fact a blade hub requires conventionally a heavy hub rimfor attachment of the blade, if the machine is to be a high speedmachine. A heavy rim in turn requires a still thicker and heavier rotordisk. When the blade is made hollow and the heavy blade hub iseliminated so that the rotor plates are again saved from stress, theseplates may be simple sheet metal structures comprising thin disks orflanged stampings from sheet metal.

The rotor plates may have a thickness of the order of the thickness ofthe blade walls or cores. They do not need to increase in thickness nearthe peripheries of the plates.

In a typical case the rotor plates are of the order of ten timesthickness of the blade walls or less.

Then each blade is attached "ice Axial flow compressor blades operatingat high tip speeds have very small nose radii of the order of tenthousandths of an inch at the tip sections and larger radii at the rootsections.

It is difficult to machine radii which vary from root to tip in any caseand especially difiicult if the blades are integral with a common hubstructure.

in this invention the radii are provided by folding a sheet of metalalong the blade leading edge over a mandrel. A thin enough sheet isselected to obtain the desired nose radii at the tips of the blades.This sheet is not strong enough to provide the proper rigidity be tweenthe leading and trailing edges of the blade. Accordingly a core memberis inserted before the trailing edge is sealed.

This core member preferably has radially extending corrugations whichcontact the walls of the blade. The corrugations are coated with asolder and fused to the blade walls.

The corrugated core or stem comprises ribs spaced apart chordwisedefining grooves of trough-shaped recesses therebetwecn. Accordingly thestem passes from one wall to the other of the blade and is fixed to thewalls along the ribs.

Referring now to the drawings the rotor is indicated generally by 10.The hub structure 12 includes the side plates 14 and 15, each having theinwardly turned flanges 16 and 18 respectively which together form a rim19 at the root ends of the blades capable of sustaining the substantialchange in density and pressure which occurs in operation between theleading and trailing edges of the blades. The blade supporting or coreplates are 20 and 22, having the corrugated cores 23 spaced peripherallyabout the hub structure. The blade plates 24, 26 have a plurality ofblade blanks 28 integral therewith and spaced peripherally about theperimeter. The blanks are folded about the leading edge line 30 to formblades 31 and 32.

After the blade blanks are folded, a core member is inserted in eachblade by spreading the blade walls apart at the rear. The blade materialis sufficiently elastic to permit this without deformation.

Since the blades are spaced peripherally close together two core platesare used with the respective cores interdigitating. For other bladespacings even more core plates may be used. For the same reason aplurality of interdigitating blade plates are employed as shown in Figs.1 and 2.

In Fig. l the blade blanks for blades 31 are integral with blade plate24. The blade blanks for the blades 32 are integral with blade plate 26.The core plate 20 carries the blade cores for blades 31 while core plate22 carries the cores for blades 32.

The stems 23 encompassed by the blade blanks as shown particularly inFigs. 1 and 2 are twisted so that the cores or stems will extendgenerally transversely with respect to the plates 20 and 22 to give theblades a pitch angle with respect to the plane of rotation.

The rotor blades of the hub structure include the side plates 14 and 15as well as the core and blade p s. The side plates have axially directedflanges suitably notched to accommodate the root ends of the blades asshown in Fig. 1. That is the blades extend outward beyond the perimetersof the side plates through the openings 46 in the flanges 16 and 18. Theroots of the blades are bonded to the flanges preferably by brazing.

The plates are bonded to a suitable hub means 50 comprising the hubelements 52 and 54 which serve for mounting the rotor on a shaft 56.

In an alternate form of the invention shown in Fig. 7 the blade blanksare individual. Each blade blank 28a is first folded about the leadingedge line 30a and then the folded blank is slipped over a blade core.The blank is then fused together at the trailing edge and to the coreand to the side plates at the root end of the blade. The hub elementsare shown at 58, 59.

Preferably the fusing or soldering process is executed in a furnacewhile all the parts are supported in proper relation. The integralnature of the core plate keeps the number of supporting fixtures to aminimum.

The rotor plates are supported in spaced relation by hollow hubstructure comprising the parts 14 and 15 which are brazed to them.

In a bladed rotor of the axial flow type adapted to interchange energywith a fluid, the leading and trailing edges both extend radiallyoutward adapting the blades to be bathed by fluid flowing across theseedges in the general axial direction.

Compressor and turbine rotors have rotor hub rims which extend axiallyalong the axial length of the blades from their leading to trailingedges to direct the flow of elastic fluid through between the blades andsustain the substantial change in fluid density and pressure be tweenleading and trailing edges which is characteristic of these rotors. Thepressures are commonly several times higher than the atmospheric oroutside pressures.

Compressor and turbine rotors also operate in elastic fluids which havehigh temperatures due to the compression and in the latter due also tothe addition of heat. The temperature due to compression requires thatthe parts of the rotors be made of metal.

While I have illustrated specific forms of my invention, it is to beunderstood that variations may be made therein and that I intend toclaim my invention. broadly as indicated by the appended claims.

What is claimed is:

I. In combination in a bladed axial flow compressor rotor, a hollowsheet metal hub structure including a side plate and a hub rim, aplurality of sheet metal core members spaced peripherally about said hubstructure each having an integral root portion extending inward throughsaid rim, said root portion being fixed to said hub structure inwardfrom said rim by a joint in radial shear, each of said core membersbeing formed to provide a plurality of radially extending ribs spacedapart chordwise, a sheet metal blade blank encompassing each said coremember therewithin to define a hollow blade, each said rib extendingalong a major portion of the span of its respective said blade, each ofsaid blade blanks being fixed to said ribs therealong by fused metal toprovide for support by said core members of said centrifugal forcesdeveloped in use in said sheet metal blades.

2. In combination in a bladed axial flow compressor rotor, a hollowsheet metal hub structure including a side plate and a hub rim, aplurality of sheet metal centrifugal stress-carrying core members spacedperiph' erally about said hub structure each having a root portionextending inward through said rim, said root portion being fixed to saidhub structure inward from said rim by a joint in radial shear, each ofsaid core members being formed to provide a plurality of radiallyextending ribs spaced apart chordwise, a sheet metal blade blankencompassing each said core member therewithin to define a hollow blade,each said rib extending along a major portion of the span of itsrespective said blade, each of said blade blanks being fixed to saidribs therealong by fused metal, said rim having a thickness of the sameorder of magnitude as said side plates and said core members.

3. In combination in a bladed axial flow compressor rotor, a hollowsheet metal hub structure including a pair of side plates havingintegral flanges thereon forming a generally cylindrical hub rim, aplurality of centrifugal stress carrying core members spacedperipherally about said hub structure each having a root portionextending inward through said rim, said root portion being fixed to saidhub structure inward from said rim by a joint in radial shear, each ofsaid core members being formed to provide a plurality of radiallyextending ribs spaced apart chordwise, a sheet metal blade blankencompassing each said core member therewithin to define a hollow blade,each said rib extending along a major portion of the span of itsrespective said blade, each of said blade blanks being fixed to saidribs therealong by fused metal, said blank extending inward through saidrim and being fixed thereto by fused metal.

4. In combination in an axial flow compressor rotor, a rotor hubstructure including a hub element, axially spaced sheet metal sideplates having parts integral therewith forming a rotor rim extendingaxially and capable of sustaining a substantial change in the densityand pressure of the working fluid, a plurality of radially extendingcentrifugal stress carrying core members spaced peripherally about saidrim and extending therethrough radially inward between said plates,means fixing the inner ends of said core members and said side plates tosaid hub element at localities substantially inward from said rim byjoints in radial shear, a hollow sheet metal blade blank encompassingeach said core member within its interior and extending radiallyinwardly of said rim, each said core member having a trough-shapedportion extending along a major portion of said blade radial length,said blade blank being fixed to said core member portion along a majorpart of the radial length thereof.

5. In combination in an axial flow compressor rotor, a hollow rotor hubstructure including axially spaced sheet metal side plates having partsintegral therewith forming a rotor rim extending axially and capable offormation by stamping, said rim providing for sustaining a substantialchange in the density and pressure of the working fluid between theleading and trailing edges of the rotor blades, a plurality of radiallyextending centrifugal stress carrying core members spaced peripherallyabout said rim and having an inner portion extending therethroughradially inward between said plates, means fixing said inner portion ofsaid members to said side plates at localities inward from said rim byjoints in radial shear, the outer portions of said core members being acorrugated metal sheet with the ribs thereof extending radially, ahollow sheet metal blade blank encompassing each said outer portionwithin its interior and fixed to the corrugations thereof, said outerportions extending along a major portion of the radial length of eachsaid blade.

6. In combination in an axial flow fluid rotor, a rotor hub structureincluding a generally cylindrical rim surface, a plurality ofcentrifugal stress carrying cores spaced peripherally about said surfaceand extending radially outward, said cores each having a portionextending radially inward beyond said rim surface fixing said cores tosaid hub structure, each said core having a plurality of spanwise ribsspaced apart chordwise defining a plurality of grooves therebetween, anda plurality of hollow sheet metal blade blanks each encompassing a saidcore therewith and contacting said ribs, each said blank extending intosaid rim but terminating short of the inner end of said cores so thatsaid cores chiefly transmit the centrifugal load from said blade blankto said hub structure, each said core extending along a major portion ofthe radial length of its respective said blade blank, each said bladeblank being fixed to said ribs within by fused metal.

7. In combination in an axial flow compressor rotor adapted to changesubstantially the density of a fluid flowing therethrough, a hubstructure comprising a sheet metal side plate and a sheet metal rimperipherally disposed thereabout, a plurality of hollow sheet metalaxial flow blades spaced peripherally about said structure, each saidblade having sheet metal walls of a thickness of the order of magnitudeof the nose radius of said blade adjacent the tip thereof, a sheet metalcentrifugal stress carrying core fixed to said blade walls within theinterior of each said blade of limited thickness of the order ofthickness of said blade walls, each said core having an inner plateportion extending radially inward through said rib to said hub structureand being fixed thereto by a joint in radial shear, said blade and coreof limited thickness and weight adapting said inner plate portion tohave limited thickness and weight of the order of thickness of saidcore, said rim extending axially along the axial length of said bladesadapting said rotor to change substantially the density of said fluidbetween leading and trailing edges of said blades.

References Cited in the file of this patent UNITED STATES PATENTSSummers Dec. 28, 1920 Jacobs Jan. 24, 1922 Doran Apr. 18, 1944 FranssonMar. 21, 1950 Franz Sept. 25, 1951 Bachle July 22, 1952 Stalker Aug. 18,1953 FOREIGN PATENTS Switzerland Sept. 17, 1945 Great Britain May 28,1948

